1. Field of the Invention
The present invention relates to a clearing bar for the clearing blade of a snowplow, which is provided, at its end facing away from the road to be cleared, with an essentially planar attachment neck, which is intended for being grasped by attachment means and fixed in place on the clearing blade, whereby at least parts of the attachment means rise out of the plane of the attachment neck in the direction of travel, and whereby the cross-section of the clearing bar is delimited, at least in the region of the attachment means, by a curved contour, which passes through an apex that lies outside of the plane between road and attachment neck.
2. The Prior Art
Such a clearing bar is known from the utility model DE 81 29 044 U1 and from the patent DE 44 04 969 B4 of the same applicant.
The clearing bar is a wear part that is affixed to the road-side end of the clearing blade of a snowplow. The clearing bar is pressed onto the asphalt, scrapes the snow from the road, and passes it into the clearing blade, which pushes the collected snow to the side.
A usual clearing bar according to the state of the art is shown in FIG. 1. The curved clearing blade 1 of a snowplow is guided along the road 2 in the direction of travel F. A clearing bar 3 is affixed to the road-side, lower end of the clearing blade 1, with which the clearing blade 1 presses down against the road 2. At its upper end, the clearing bar 3 has an essentially planar attachment neck, with which the clearing bar 3 is attached to the clearing blade 1. Attachment takes place using attachment means 5 that grasp the clearing bar in the region of the attachment neck 4 and fix it in place on the clearing blade 1. The attachment means 5 are generally screws (as shown in FIG. 1 and in the case of DE 81 29 044 U1) or clamping claws that grasp the clearing bar over a large area and press it against the lower end of the clearing blade 1. DE 30 38 121 A1 shows clamping claws. Furthermore, special attachment means are known, for example from DE 101 47 393 A1 of the same applicant.
When it is advanced in the direction of travel F, the clearing bar 3 loosens snow 6 that is lying in the road 2, and passes it upward in the direction of the curved clearing blade 1. Particularly in the case of snow removal trips on highways, which are carried out at speeds above 40 km/h, not insignificant snow turbulences within the clearing blade occur; offshoots of these turbulences can reach the windshield of the clearing vehicle and can cover it with snow. The driver's vision is significantly restricted by this. In the patent literature, some references are known that concern themselves with keeping the snow turbulence that forms in the clearing blade away from the windshield. Examples that can be named in this regard are U.S. Pat. No. 5,309,653 and DE 299 01 383 U1.
These two references describe great apparatus effort for limiting the effects of the snow turbulence that occurs in the clearing blade. However, they do not recognize and treat the actual cause of the problem. This can be seen in the parts of the attachment means that rise out of the plane of the attachment neck. These parts—in FIG. 1, the screw head 7—represent a flow resistance on the clearing bar 3, which is otherwise planar. The snow 6 that is taken up is swirled up in a turbulence zone 8, directly below the screw head 7, so that a highly turbulent flow of snow occurs in the clearing blade 1, offshoots of which cover up the windshield, unless suitable interception devices are provided.
Even though screw heads, in particular, take up only a small proportion of the total width of a clearing bar, studies by the applicant have shown that even these small flow resistances at the transition between clearing bar and clearing blade exert a significantly negative influence on the flow of snow within the clearing blade. When using clamping claws, this problem occurs to an even more unpleasant extent. This holds true not only for clearing bars having a completely planar front, such as the example shown in FIG. 1, but also for clearing bars having a curved contour, in cross-section, as they are known from DE 81 29 044 U1 or DE 44 04 969 B4. As long as the contour is curved in the manner disclosed there, the flow of snow is also guided past the attachment means, and for this reason, turbulence occurs here, as well.
From the German utility model DE 1 959 940 U1, a clearing blade having a clearing bar made of a resilient material is known. The clearing bar has a flat, block-shaped form when not in use; in clearing operation, it is pressed against the road by the clearing blade, and is greatly deformed in this process. In the deformed state, its cross-section is partly delimited by a curved contour that makes a transition into a linear section, in a projecting corner point. The corner point results from the edge between front side and narrow side of the non-deformed clearing bar. The flow of the snow breaks off, in uncontrolled manner, as a result of the non-constant transition of the linear section into the curved contour, so that the snow is swirled up in diffuse manner here. Furthermore, the corner point is comparatively far removed from the projecting part of the attachment means, so that the flow of snow is broken up again by the attachment means, after it has swirled around the corner point.
DE 296 22 102 U1 pursues the goal of disposing the attachment means on the back of the clearing bar, to the greatest possible extent, in order to put up as little resistance as possible to the flow of the snow masses that is directed upward. This does not succeed completely, since clamping screws are required for the solution proposed there, whose heads continue to have the snow masses flow around them. For the remainder, it is also pointed out that flow resistances lead to turbulences in and above the clearing blade that impair vision.
WO 95/23894 A1 describes a snow plow whose clearing bar is mounted in the clearing blade so as to pivot. The clearing bar itself is planar and connected with a carrier plate without any projecting parts of an attachment means, possibly by means of gluing, welding, or vulcanization. A flexible rubber flap, which is curved during clearing operation, closes off the movement region of the clearing bar in the clearing blade. Due to the absence of projecting parts, undisturbed flow of the snow from the clearing bar into the blade should be expected. However, this is achieved at the price of incompatibility of the clearing bar with conventional plows. Furthermore, replacement of this clearing bar after it has become worn is significantly more complicated, because of its material-fit connection with the articulated mounting.